Keith Olbermann, the former top-rated host of MSNBC’s “Countdown,” announced Tuesday that he will join the public affairs channel Current TV.

“Greetings from Keith Olbermann, Chief News Officer of Current Media,” he wrote on his Twitter account Tuesday morning. “And awayyyyyy we go!”

Olbermann will be executive producer and host of a “new nightly primetime news and commentary show beginning later in 2011” and serve as the channel’s Chief News Officer, as well as having an equity stake in its parent company, Current Media, according to a press release.

The name of his upcoming show and its airtime were not revealed.

People familiar with Olbermann’s plans suggested Monday that he was likely to join the cable network, which was launched in 2005 by former US Vice President Al Gore and businessman Joel Hyatt.

On a conference call Tuesday announcing the move, Gore noted that, “We have more subscribers today than MSNBC had when Keith began working for them [in 2003].”

Olbermann abruptly left MSNBC in January, less than three months after the network briefly suspended the fiery host for making three donations to Democratic candidates without seeking approval beforehand.

On his Twitter account, Olbermann has been teasing his followers about what the future held with messages such as “As indicated by the preface ‘LOL,’ tomorrow’s announcement is NOT on ESPN. That was a LeBron James reference that… never mind.”

And: “OK it’s true! I’ve signed with the Yankees. I’m competing with Freddy Garcia and Bartolo Colon for the 5th Starter’s job.”

In a statement on Current TV’s website, Olbermann wrote: “Nothing is more vital to a free America than a free media, and nothing is more vital to my concept of a free media than news produced independently of corporate interference. In Current Media, Al Gore and Joel Hyatt have created the model truth-seeking entity. The opportunity to partner with Al, Joel and Mark Rosenthal makes this the most exciting venture in my career.”